A new extracorporeal blood pump design was built an tested in Phase I. The pump was compared to the standard roller and centrifugal pumps under a variety of conditions for safety, hemolysis, efficiency, and durability. The new pump has many desirable properties which are not found in the other current pumps, including inherent pressure regulation (i.e., will not over pressurize or generate hazardous negative pressures), the lowest consumption of energy for the same output, and excellent durability. A venturi flowmeter design was tested for accuracy and hemolysis, and the results have demonstrated that the flowmeter is extremely accurate with very low hemolysis. The objective of Phase II is to research aspects of the pump system that will be important for eventual commercial application. The research will focus on materials, geometry, and manufacturing techniques used in the pump chambers, and the design of the pump hardware and required controls. Pumps will be designed with the appropriate size, pressure, and flow requirements to incorporate into application-specific systems for cardiac surgery, hemodialysis, pumped hemofiltration, and apheresis. In vitro and in vivo testing will be completed for performance, safety, hemolysis, and durability. The final designs will be ready for pilot manufacturing and subsequent FDA trials.